Internal combustion engines having rotary valves provided with combustion chambers are disclosed by C. N. Hansen and P. C. Cross in U.S. Pat. Nos. 4,612,886; 4,773,364; 4,813,392; 5,000,136; and, 5,081,966. The rotary valves disclosed in these patents do not have any structure or methods for varying the intake valve timing. Conventional throttle plates are used to control the flow of air/fuel mixture to the combustion chambers of the rotary valve. Hydrocarbon fuel engine efficiencies can be improved by reducing the engine's pumping losses. The pumping losses contribute significantly to the lowering of the engine's operational efficiency and are negative work required by an engine to pump air through it. The pumping losses are due primarily to the resistance associated with the air as it flows past the throttling valve of a conventional carburetor on its way to the combustion chamber. The standard spark/ignition engine is most efficient when it is at wide-open throttle where the pumping losses are minimal. In the speeds of the typical motor vehicle engine, the majority of its time of operation is at part/throttle and idle. The elimination of the throttling process of an internal combustion engine by running the engine at wide-open throttle throughout its load/speed range improves the average overall efficiency of the engine by approximately twenty percent.
Variable valve timing is the scheduling of the valve timing events throughout an combustion engine's load/speed range. Electronically operated variable cam shafts used with poppet valves have been designed to regulate the amount of air/fuel mixture available for the combustion process. The load control of the engine is maintained without a throttle valve. Disclosures of examples of this type of variable valve timing apparatus is found in U.S. Pat. No. 4,774,913 and U.S. Pat. No. l5,209,194.